TRANSPORT OF LARGE NUCLEAR POWER PLANT COMPONENTS - EXPERIENCES IN MECHANICAL DESIGN ASSESSMENT - Presentation

In the course of decommissioning of nuclear power plants in Germany large nuclear components must be transported over public traffic routes to interim storage facilities. In dependence of classification of the package it is necessary to subject the package to different mechanical tests according to the transport regulations. Since it concerns surface contaminated objects (SCO) or low specific activity materials (LSA), a safety evaluation considering the IAEA transport regulations mainly for industrial packages (Type IP-2) is necessary. For Type IP-2 packages the mechanical assessment under normal conditions of transport is required - a free drop of the package onto an unyielding target and a stacking test has to be investigated. Large components are unique packages, therefore it is not possible to choose experimental testing as assessment method. The application of a complex numerical analysis for mechanical proof is necessary. The assessment of the loads takes place on the basis of local stress distributions, also with consideration of radiation-induced brittleness of the material and with consideration of current scientific investigation results. The large nuclear components have typically been transported in an unpackaged manner, so that the external shell of the component provides the packaging wall. According to the present IAEA regulations the drop position is to be examined, which causes the maximum damage to the package. In case of a transport under special arrangement a drop only in an attitude representing the usual handling position is necessary. The paper will represent the methods, which are used for the evaluation of the mechanical integrity of the package for transport approval and will present recent transports of a reactor pressure vessel and of steam generators in Germany.